What are the chances of TB?
Farmers should start watching deer movement and be aware of deer attractants on their farm to protect their cattle herd from being infected with TB.
Bovine Tuberculosis (TB) keeps claiming cattle herds. The evidence shows that the disease comes into cattle herds primarily from infected deer that eat something and leave saliva behind. Cattle that then have access to that same feed area may become exposed to the bacterium that causes TB.
As much as we have learned, and in spite of the steps we have taken, we are still recording two to four infected herds each year. There were three in 2015, in Alpena and Alcona Counties. Already in 2016 there has been one in Oscoda County. Each new herd infection is traumatic.
Michigan State University Extension, works with a small group of professionals to visit farms and look at the possible enticements and opportunities for deer incursion that may provide a means of transmission of the disease to cattle. That group includes a veterinarian with the Michigan Department of Agriculture and Rural Development, a wildlife biologist with USDA and a local farmer. They are committed to reducing new herd infections.
Farms voluntarily chose to participate in this assessment. We have gone to various farms and walked the premises with the farmer and in that process, have learned some things that are worth sharing.
Deer movement, while not fully predictable, does have seasonal and diurnal patterns. Pay attention to those movements. And where those movements bring deer close to the farmstead or to cattle areas, then consider fencing to deter deer.
If deer have already found a source of feed on a farm, whether that is feed in storage or already dispersed for cattle to eat, they will be very hard to dissuade from returning. The need for more exclusionary fencing (8 or 10 feet) is greater than when we are just trying to encourage deer to stay out of an area that they travel for convenience.
Be aware of deer attractants on the farm. One of the most overlooked deer attractants is apple trees. Deer love apples and will come to get them. That may bring them into pastures or close to farmsteads. Other attractants may be waste feed that is piled up nearby. When deer are close to farmsteads they may look around and see other feed that they can access. That may provide the opportunity for transmission to cattle.
Farmers need to recognize the impact of changes occurring on other farms or in the wild. If food availability changes in the area, for example because a neighbor fenced off stored feed that deer were getting into, or because the acorn crop is reduced, then deer will break their usual patterns to seek food.
We have emphasized with farmers that it is not the usual situation in which we are most interested; it is the unusual or the potential situation. While it may be the case that deer regularly visit some areas of farms, the reality is that most producers have discouraged or prevented those regular visits. Now we are trying to identify what may happen irregularly or unusually. All it takes is one exposure of cattle to the saliva left behind by a TB-infected deer.
Dairy and beef cattle farming in an area where the wild population of deer has TB, even though only a small percentage of deer are infected, is difficult. The risks are high and therefore, it is essential to work even harder to prevent the possibility of the disease being transmitted to the herd.
TB is a community problem. We need each other in order to eliminate this threat. The hunting of deer provides a means of thinning the herd and a sentinel for the prevalence within that wild population. We also need to stop supporting the artificial feeding of deer that maintains the population above the carrying capacity of the woods, just because people like to see deer. The fact is that the livelihoods of farmers may be at risk because of that feeding.
Farmers need to work together to eliminate opportunities for deer within communities and to cull deer that venture onto their farms. Communities of people working together on this problem can accomplish more than individuals ever will. The goal is a disease-free wild deer herd and disease–free cattle herds. That is a benefit for all.